Dishwasher

ABSTRACT

A dishwasher includes a washing chamber and at least one spray arm rotatably mounted in the washing chamber. The at least one spray arm is provided with a plurality of nozzles, each configured to spray wash water in a respective spray jet. The plurality of nozzles are supplied with wash water by a pump. A flow obstacle is disposed in the spray arm upstream of a first nozzle of the plurality of nozzles and configured to change a geometry of the respective spray jet.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a U.S. National Phase application under 35 U.S.C. §371 of International Application No. PCT/EP2008/006260, filed on Jul. 30, 2008 and claims benefit to German Patent Application No. DE 10 2007 038 469.8, filed on Aug. 14, 2007. The International Application was published in German on Feb. 19, 2009 as WO 2009/021626 A1 under PCT Article 21(2).

FIELD

The present invention relates to a dishwasher having a washing chamber in which is rotatably mounted at least one spray arm.

BACKGROUND

European Patent Application EP 1 040 786 A1 describes a dishwasher having pulsed nozzles, in which one arm has a plurality of nozzles which are supplied with each other with wash water via different channels. One channel is in communication with what is referred to as auxiliary nozzles. The supply of wash water to said auxiliary nozzles can be shut off by a valve. This enables the wash water to exit in pulses, partially preventing wash water from being sprayed out of the auxiliary nozzles.

German Patent Application DE 10 2004 018 878 A1 describes a dishwasher having a spray arm in which individual spray nozzles can be activated and deactivated without using additional actuators. This enables the spraying of the dishes to be pulsed according to the variation of the pump pressure to allow for effective cleaning. To this end, elastic means are provided which are capable of opening and closing the individual nozzles. However, the known nozzles have the problem that the spray jet always exits in a manner that corresponds to the nozzle opening. No provision is made to change the geometry of the spray jets and, therefore, the spray jets cannot effectively reach problem areas, for example in pots, corner areas of the washing chamber, or other areas that are difficult to access. This is because, although pulsed operation is possible, the exiting spray jet still has a given geometry.

The dishwasher proposed in DE 10 2005 026 558 B3 uses at least one spray arm within which a rotating element creates pulsed spray jets.

European Patent Application EP 1 334 687 A1 describes a spray arm having spray nozzles whose spraying characteristics can be changed by plate-shaped actuation elements. To this end, a manual operation is required of the user.

SUMMARY

In an embodiment, the present invention provides a dishwasher including a washing chamber and at least one spray arm rotatably mounted in the washing chamber. The at least one spray arm includes a plurality of nozzles. Each nozzle is configured for spraying wash water in a respective spray jet. The plurality of nozzles are supplied with wash water by a pump. A flow obstacle is disposed in the spray arm upstream of a first nozzle of the plurality of nozzles and configured to change a geometry of the respective spray jet.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the present invention is shown in the drawings in a schematic way and will be described in more detail below. In the drawings:

FIG. 1 is a cross-sectional side view of an exemplary embodiment of a spray arm according to the present invention;

FIGS. 2A through 2E are detail views showing different flow obstacles for a spray arm;

FIG. 3 is a cross-sectional side view of a second exemplary embodiment of a spray arm according to the present invention;

FIGS. 4A and 4B are detail views of the spray arm of FIG. 3, showing a flow obstacle in different positions;

FIG. 5 is a cross-sectional side view of a spray arm according to a third exemplary embodiment;

FIG. 6A is a detail view of a flow obstacle of the spray arm of FIG. 5; and

FIG. 6B is a detail view of a modified flow obstacle for a spray arm according to FIG. 5.

DETAILED DESCRIPTION

An embodiment of the present invention provides a dishwasher in which, the spray arms have a simple design. The jets of wash water sprayed from the spray arms can be at least partially adjusted.

In accordance with the present invention, a flow obstacle is provided within the spray arm upstream of at least one nozzle to change the geometry of the spray jet. It has been found that the geometry of the exiting spray jet can be changed by a flow obstacle that is disposed within the spray arm proximate to the nozzle, so that the spray jet can not only issue from the spray arm in a straight line, but may also have other geometries, increasing the cleaning performance. It is especially by changing the geometry of the spray jet that hard-to-access areas, such as in pots or in corners, can be reached effectively.

In a preferred embodiment of the present invention, the spray arm takes the form of a hollow member, and a flow obstacle is held to the inner wall of the hollow member opposite the nozzle. As a result, defined flow channels are created within the spray arm, so that the exiting fluid forms a spray jet that corresponds to the configuration of the flow obstacle and the nozzle. In order to minimize the influence of pressure fluctuations, the flow obstacle may extend into close proximity to the exit area of the spray jet at the nozzle, for example to a distance of less than about 4 mm therefrom.

In accordance with another embodiment of the present invention, the flow obstacle is movable relative to the nozzle located in the vicinity thereof. This allows the shape of the spray jet to be adjusted, it being possible for the adjustment to be made either manually prior to the washing process or automatically, for example, depending on the pressure.

Preferably, the spray arm is provided with a plurality of distributed nozzles which are each associated with a flow obstacle. This allows a suitable flow obstacle to be associated with a nozzle depending on the location of the nozzle. For example, in an outer region, it is advantageous to provide flow obstacles that create a slightly wider spray jet, while nozzles disposed in the radially inner region of the spray arm may rather produce a narrower, stronger jet.

The flow obstacle may preferably be in the form of a peg having a rounded surface, so that a conical spray jet will be produced. It is also possible for the flow obstacle to take the form of a V-shaped ramp, a helix, or a pin, so as to produce a particular spray jet.

A spray arm 1 is disposed in a washing chamber of a dishwasher. The spray arm takes the form of a hollow member 2 and is provided at a central opening with a coupling portion 3 for connection to a conduit system of the dishwasher. Thus, wash water can be pumped into spray arm 1 by a pump. Coupling portion 3 is located at a central axis of rotation A of spray arm 1.

A first wall 4 of hollow member 2 has formed therein a plurality of nozzles 5 via which the wash water can be sprayed onto items to be washed. Further, one or more driving nozzles 6 may be provided to allow spray arm 1 to rotate during the washing operation. Nozzles 5 may point upward, as shown in the figures. Alternatively, they may be directed downwardly to provide for the cleaning of items located under the spray arm.

Within hollow member 2, flow obstacles 8 are provided upstream of at least some of nozzles 5, said flow obstacles extending from opposite wall 7 of hollow member 2 toward nozzles 5. Each flow obstacle 8 is associated with one nozzle 5.

The function of the flow obstacle is described with reference to FIGS. 2A through 2E.

FIG. 2A shows a nozzle 5 of a spray arm, such as is used in the prior art. Nozzle 5 points upward and has an exit area 9 through which the wash water exits as a concentrated jet 10. The intensity of wash water jet 10 can be varied by the volumetric flow rate, but its geometry cannot be changed in this manner. Consequently, the shape of the jet remains unchanged.

In FIG. 2B, spray arm 1 of the present invention is shown along with flow obstacle 8, which is in the form of a peg and has a rounded surface, preferably in the form of a hemisphere, which is disposed proximate to nozzle 5. Flow obstacle 8 is disposed immediately proximate to nozzle 5 upstream of circular exit area 9 to influence the flow of wash water on its way into nozzle 5. Because of this, the shape of a jet 11 from nozzle 5 is changed, peg-shaped flow obstacle 8 causing the jet to exit from exit area 9 in the shape of a cone. This jet shape allows a larger area to be reached by wash water.

In FIG. 2C, a modified flow obstacle 18 is disposed in spray arm 1, said modified flow obstacle taking the form of a thin pin which projects through nozzle 5. A tip 19 is located outside exit area 9 of nozzle 5. Since this flow obstacle is configured as a thin pin 18 projecting through exit area 9, a spray jet 20 is produced which has the shape of a hollow cone. Because of the conical spreading of the jet, on the one hand, the spray covers a relatively large area and, on the other hand, the volumetric flow rate in the region of the outer surface of hollow-cone jet 20 is greater than that in a full-cone jet 11.

FIG. 2D shows an exemplary embodiment for a flow obstacle 28, where a ramp is formed on bottom 7 of the hollow member, the ramp extending in a wall-like manner and being V-shaped in the region proximate to nozzle 5, forming sloped surfaces 29 extending toward nozzle 5. Because of this, spray jet 30 exits from exit area 9 as a flat jet 20 which widens in the shape of a wedge.

FIG. 2E shows another embodiment for a flow obstacle 38, which is configured as a helix and provided with a helical channel 39. The helix terminates in close proximity to exit area 9 of nozzle 5, so that exiting jet 40 is a swirling jet.

In the embodiments of FIGS. 2B through 2E, flow obstacles 8, 18, 28 and 38 each act as a restrictor for nozzle 5, so that, due to the predetermined flow conditions in the vicinity of nozzle 5, spray jets 11, 20, 30 or 40 are produced which each have a specific geometry, which may also be dependent on the volumetric flow rate. Furthermore, the variation of the geometry of the spray jet makes it is possible to reach hard-to-access areas within a washing chamber of a dishwasher. In this exemplary embodiment, adjustment is not possible because flow obstacles 8, 18, 28 and 38 are fixedly attached to bottom of 7 of spray arm 1.

In the exemplary embodiment shown in FIG. 3, a spray arm 1 is provided which, again, takes the form of a hollow member 2 having a central coupling portion 3, said coupling portion 3 being disposed along a central axis of rotation A. Hollow member 2 is provided in its upper wall 4 with nozzles 5, and in addition has one or more driving nozzles 6. Here, flow obstacles 8′ are provided within hollow member 2, each of said flow obstacles extending from opposite wall 7 toward a nozzle and being adjustably held to bottom 7 of spray arm 2. Flow obstacle 8′ is in the form of a peg having a rounded surface, said peg 8′ being formed with an external thread 9′ which engages with a thread (not shown) in wall 7. This allows the flow obstacle to be moved closer to nozzle 5 or away from nozzle 5 by rotating peg 8′.

In FIG. 4A, peg 8′ is moved away from nozzle 5 using a tool engaged with a slot 10′, thereby reducing the influence on the flow path of the wash water, and thus changing the geometry of the spray jet exiting from nozzle 5.

FIG. 4B shows peg 8′ in a position where the hemispherical surface is disposed in immediate proximity to nozzle 5, so that a relatively strong influence is exerted on the flow path of the wash water to nozzle 5, as a result of which the geometry of the exiting jet diverges to a greater degree than in the position shown in FIG. 4A. Thus, the user can adjust the geometry of the spray jet by manually turning pegs 8′ further into or out of spray arm

The flow obstacles shown in FIG. 3 are in the form of pegs 8′. However, flow obstacles 18, 28 and 38 shown in FIGS. 2C through E may, of course, also be provided at the individual nozzles 5, as needed.

FIG. 5 shows a further embodiment of a spray arm 1 according to the present invention, said spray arm taking the form of a hollow member 2 and having a coupling portion 3 extending around a central axis of rotation A. Hollow member 2 has a plurality of nozzles 5 distributed along its length and is further provided with driving nozzles 6 to provide rotational drive thereto.

Pegs 8″ having a rounded surface are provided as flow obstacles proximate to nozzles 5. However, these pegs are not fixedly attached to wall 7 of hollow member 2 opposite nozzles 5, but can be moved by a spring member 9″. Because of this, the distance of flow obstacle 8″ from nozzle 5 is dependent on the pressure within spray arm 1, so that at a higher pump speed, flow obstacles 8″ are pushed further away from nozzle 5 than at a lower pump speed. Thus, the spray jet from nozzles 5 is varied depending on the pressure within spray arm 1.

FIG. 6A is an enlarged view illustrating the mounting arrangement of flow obstacle 8″ shown in FIG. 5. Peg 8″ is supported on a helical spring 9″, preferably of steel, spring 9″ being supported in a receptacle 10″ on wall 7 of spray arm 1″.

According to FIG. 6B, it is also possible to provide a diaphragm 9′ on wall 7 of spray arm 1, a flow obstacle 8″' in the form of a peg being movably supported by said diaphragm.

When flow obstacles 8″ or 8″' are resiliently mounted, the geometry of the flow obstacles can also be selected relatively freely. In particular, the flow obstacles shown in FIGS. 2C through 2E may also be resiliently mounted.

In the exemplary embodiments shown, flow obstacles 8 or either fixedly, adjustably or resiliently supported on bottom 7. Of course, it is also possible to provide a spray arm with different flow obstacles 8, some of which are fixedly supported, some of which are adjustably supported, and some of which are resiliently supported. In addition, the flow obstacles within one spray arm may have different geometries, which allows spray jets having different geometries to be produced at the individual nozzles 5. In this connection, nozzle 5 may be provided with a slit opening, or with an opening having a different geometry, in place of a circular exit area.

While the invention has been described with reference to particular embodiments thereof, it will be understood by those having ordinary skill the art that various changes may be made therein without departing from the scope and spirit of the invention. Further, the present invention is not limited to the embodiments described herein; reference should be had to the appended claims. 

1-12. (canceled)
 13. A dishwasher comprising: a washing chamber; at least one spray arm rotatably mounted in the washing chamber, the at least one spray arm including a plurality of nozzles each configured to spray wash water in a respective spray jet, the plurality of nozzles being supplied with wash water by a pump; and a flow obstacle disposed in the spray arm upstream of a first nozzle of the plurality of nozzles and configured to change a geometry of the respective spray jet.
 14. The dishwasher as recited in claim 13, wherein the spray arm includes a hollow member and the flow obstacle is disposed near an inner wall of the hollow member opposite the first nozzle.
 15. The dishwasher as recited in claim 13, wherein the flow obstacle extends into close proximity of an exit area of the respective spray jet at the first nozzle.
 16. The dishwasher as recited in claim 13, wherein the flow obstacle is movable relative to the first nozzle and disposed in a vicinity thereof.
 17. The dishwasher as recited in claim 13, wherein the plurality of nozzles are distributed, and further comprising a second flow obstacle associated with a second of the plurality of nozzles.
 18. The dishwasher as recited in claim 13, wherein the flow obstacle includes a peg having a rounded surface.
 19. The dishwasher as recited in claim 13, wherein the rounded surface includes a form of a hemisphere.
 20. The dishwasher as recited in claim 13, wherein the flow obstacle includes a V-shaped ramp.
 21. The dishwasher as recited in claim 13, wherein the flow obstacle includes a helix configured to swirl the wash water upstream of the first nozzle.
 22. The dishwasher as recited in claim 13, wherein the flow obstacle includes a pin projecting into an exit area of the respective spray jet at the first nozzle.
 23. The dishwasher as recited in claim 13, wherein the flow obstacle is adjustable in position relative to the first nozzle and disposed in a vicinity thereof.
 24. The dishwasher as recited in claim 13, wherein the flow obstacle is movably supported by a spring.
 25. The dishwasher as recited in claim 13, wherein the flow obstacle is associated with the first nozzle, and further comprising a second flow obstacle different than the flow obstacle and associated with a second nozzle of the plurality of nozzles. 